.cover-box {
    position: relative;
    display:block;
    width: 100%;
    height: 100%;
    visibility: visible;
    overflow: hidden;
    img {
        position: absolute;
        top:0;
        left:0;
        width: 100%;
        height: 100%;
        transition-property: transform;
        transition-duration: 0.5s;
    }
    .mask {
        position: absolute;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        opacity: 0;
        background-color: #000;
        //z-index: 1;
        transition-property: opacity;
        transition-duration: 0.5s;
    }
    .play-btn {
        position: absolute;
        left: 50%;
        top: 50%;
        margin: -35px;
        width: 70px;
        height: 70px;
        background-image: url(cover_play.png);
        opacity: 0;
        transform: scale(0.3);
        transition-property: opacity,transform;
        transition-duration: .5s;
        // &:hover {
        //     opacity: 1;
        //     transform: scale(1) translateZ(1);
        // }
    }
    &:hover {
        .play-btn{
            opacity: 1;
            transform: scale(0.7);
        }
        .mask {
            opacity: .5;
        }
        img {
            transform: scale(1.3);
        }
    }
}